Process of and apparatus for refining zinc



l 2 Sheets-Sheet 1. M. HOLSTEIN J. D. JAMES; P'ROGBSS OIAND APPARATUSFORBEFINING ZINC.

(No Model.) .Y

Patented Fe A wmvfssss.'

Afro/mns.

(No Model.) 2 Sheets-Sheet 2.

G. M. HQLSTEIN x44. D. JAMES. PROCESS OP AND APPARATUS POR REPININGZINC.

/N VE N TOHS A TTUHNEYS.

Nirnn STATES ATENT Enron.

GEORGE M. HOLSTEIN AND JOHN D. JAMES, OF PULASKI CITY, VIRGINIA,ASSIGNORS, BY DIRECT AND MESNE ASSIGNMENTS, TO Tl-IE BERTH'A MIN- ERALCOMPANY, OF JERSEY CITY, NEYV JERSEY.

PROCESS OF AND APPARATUS FOR REFINING ZINC.

i SECIFICATION forming part of Letters Patent- No. 554,184, datedFebruary 4, 18S-)6.v

Application filed May 27, 1895.

To @ZZ whom it ,1m/,y concern:

Beit known that we, GEORGE M. HOLSTEIN and JOHN D. JAMES, of PulaskiCity, in the county of Pulaski and State of Virginia, have invented anew and useful Improvement in Processes of and Apparatus for RefiningZinc, of which the following is a speciiication.

The object of our invention is to provide a process and apparatus forreiining zinc spel- 1o ter, and more especially for separating therefromthe lead with which it may be contaminated and it consists in certainsteps for carrying out the same based upon the relative specificgravity, the melting-points, and volar 5 tilizing-points of these twometals, and a special construction and arrangement of furnace andretorts for making the same practically available, as will behereinafter more fully described with reference to the drawings, in zoWhich- Figure lis a front elevation of aportion of the furnace; Fig. 2,a vertical section through a portion of the retorts, condensers, andtheir front and back supports; Fig. 3, a rear View 2 5 of a part of theback end wall or supportingshelves for the back ends of the retorts,partly broken away; and Figs. 4, 5, 6, and 7 are details ofmodifications.

In the drawings, Fig. 2, A A represent the 3o retorts made of clay andbaked in the usual manner, and having their back ends c closed, andtheir front ends provided with the tapering conical condensers B, intowhich the volatilized zinc is condensed and collected when 3 5 distilledfrom the retorts. These condensers are luted or cemented temporarily inthe open ends of the retorts with a paste of clay, and are of the usualconstruction, being made at the lower edges of their larger open endwith 4o a semicircular bridge wall or dam b which prevents the boilingmetal in the retorts from slopping over into the condenser, and alsoprevents the pure distilled and molten zinc in the condenser fromrunning back into the retort.

The outer and smaller end of this condenser is partly closed witha'sto'pple b of clay, which is removed when the contents of thecondenser are to be drawn off.. l l i The outer ends of the retorts areheld in a Serial No. 550,811. (No model.)

front wall composed of an inner lining C, of fire brick and clay, and afacing of cast-iron boxes C through which the condensers protrude, thewhole being arranged to form a bank or nest ofretorts, condensers andboX- frames, as shown in Fig. 1, which are secured in place in the usualmanner by iron buckstays and tie-rods, and thus integrally organized.

At the back end the retorts are surrounded by a luting E2 ofclay and areentered into and supported upon a checker-work or skeleton frame offire-brick composed of horizontal tile-blocks D of fire-brick andvertical standards E of the same material having concave side and tenonsat top and bottom, as shown in Fig. 3. These iire-clay nests protrudebeyond the back ends of the retorts far enough to receive an outer capor covering of tire-clay tile or brick. This cap may be made in onepiece, as shown at F, or be built up from bricks or sectional tile, asshown at F. In either case this closure or cap at the-back end of theretort only covers the upper portion of it,`

leaving the lower portion exposed for the purpose hereinafter described.In building this wall at the back end of the retorts in large furnacesWe propose, for the purpose of greater stability, to incorporate an ironframe G therein, as shown in Figs. 5 and 6, which frame has thefire-brick packed in its cells.

Havingthus described the construction of the furnace, we will now showhow the process is carried out therein, and first let it be understoodthat we cant or incline all of the retorts, so that their back ends areabout four inches lower than their front ends, as shown in Fig. 2.

The zinc spelter in the form of bars having been rst charged into theretorts, the heat from the subjacent iire circulating up through theretort causes it to melt and assume a level, (shown by the dotted linein Fig. 2,) and then as the proper temperature is reached the zincvolatilizes, and, passing over into the condensers, is collected in theform of pure melted zinc.

The furnace lires are so regulated as to keep the retorts as nearly aspossible at the temperature at which zinc volatilizes, (1,04E0Ocentigrade,)'lead, .the chief impurity which this process is designed toremove, requiring a slightly higher temperature to volatilize. As soonas the spelter begins to melt, the lead, owing to its lowermelting-point (330O centigrade as compared with zinc i12o centigrade)and 'owing also to its greater specilic gravity, (lead, 11.37, Zinc,7.3,) collects in the lowest part of the retort at the back end. Thispart of the retort, it will be seen, is partly exposed to the air, whichchills or lowers the temperature of the metal within. This, it will beseen, by diminishing ebullition at this point, gives the necessarycondition of quiescence in the molten metal,and the greater specificgravity of the lead has a chance to assert itself and carry the lead tothe-bottom, andthe cooling of the exposed .end of the retort also solowers the temperature as to get below the volatiliZing-point of lead,so that the latter is not carried over into the condenser with the zinc,-which is thus .distilled ina condition of almost perfect'purity,running from 99.80 4to 99.98 per cent. of pure zinc. A proper regulationof the temperature-of the furnace is all that is required from ,thisstage of the treatment on to maintain and continue the separation of thelead from the zinc.

The zinc volatilizing passes over the bridge into the condenser, whereit `condenses into the molten condition, and so `remains until drawn.offer ladled out.

Thelead kept-in the coolestpart of the retort .i-sinot volatilized, .butinpart is absorbed by the silica of the retort forming lead silicate,and in part remains at the lowest end ofthe retort, as metallic lead,and at intervals is yremoved with rabbles vthrough the vfront end oftheretort. :In vour'vprocess it willfbe seen that there-are two(3o-operating and lnecessary features to our invention. One is themaking of the backend of the retort lower than the front end, soas tocause the molten metal to `flow to that end, and the. other isthezexposure and chilling of that end of theretort, so. as to takeadvantage .of the distinguishing `physical qualities of lead-17. c. ,itsgreater specific gravity, its lower melting-point, -and its highervolatilizing-point-that .is to say, lead having alowermelting-pointiirst melts and runs tothe back end of'retort, and,having'a higher volatilizing-point, the chilled end of the retort keepsit from volatilizing and also promotes such quiescence inthe moltenmetal at this point as to facilitate the separation of lead into a lowerlayer by virtue of its greater specific gravity.

Ordinarily the backends of the retorts are the hottest, because they arearranged centrally in the furnace. In our invention the back ends of theretorts are in an outside wall and exposed to the airat certainpoin'ts.Ve prefer to expose-the lower edge of the retort,

as shown in Figs. 2 and 3, for the reason that the molten metal is inthis lower plane, while the volatilized pure zinc occupies the upperzone or layer and should not be chilled since its continuousvolatilization is necessary to its separation. le also in some casesform a small channel d in the supporting-tile D beneath the retort,which lets air in and further chills this end. We find good results,however, following the chilling of any portion of the back end of theretort, and in some case we expose the upper edge of the back end of theretort, as shown in Fig. 4. This is not because it is most desirable initself, but it affords us another means of charging the metal plates ofspelter into the retorts, for in such cases we make an opening o in theupper part of the back end ofthe retort large enough to receive the fullsize pig or plate of spelter, whichis at .once charged into the retortwithout'beingA remelted intozsmaller bars, as is necessary when thespelter is charged into the retort through .the relatively .smallopening of the `condenser at theotherend. This opening-o-isduring theprocess closed up witha mixture'of an equal bulk of clay andcoal-dust,which is made firm by ironing with a hot iron after being -applied tothe opening.

As a further modification for chilling the back end ofthe retort we mayemploy a water-jacket, as shown in Fig. 7, in'which the water-chamber A2is supplied with a flowing bodyof vwater through suitable inlet andoutlet pipes.

We Vdo not confine our inventionto separating lead from zinc, as it isobvious that any other metals having similar relative characteristicsmay beseparated bythe/same process and apparatus,

Having thus described your invention, what we claim as new, and desiretosecure by Letters Patent, is-

l. The process'herein described of refining Zinc and separating it fromlead, which consists in melting the spelter and causing the lead by itslower melting-point greaterspecc gravity and higher volatilizing-pointto flow to a lpoint of lower level, chilling the metal at this point, tohold the lead below its volatilizing-point, and volatilizingandseparatin g the zinc ata temperature below the volatilizingpoint oflead substantially as shown and described.

2. A-rening-furnace for zinc having retorts with one end lower than theother, and having 4at their lower ends a supporting-wall with openingsthrough it which` are opposite to the lower part of that end-of theretort, the said wall covering. and inclosing the upper part of saidendof the retort'substantially as andfor'the-purposes described.

3. .A refining-furnace for zinc having re torts with oneend lower thanthe other, and having at their lower ends a supporting-wall providedwith an opening (l passing entirely IOO IIO

through the said wall below the bottom of the lower endof the retortsubstantially as and for the purposes described.

4. A refining-furnace for zinc having re torts with their back endslower than their front ends, a back wall composed of horzontal tile D,and Vertical tile E with tenoned ends tted to the horizontal tile so asto form un open wall or support, and a. detachable cap or lling of tileor brick covering a por- 1o tion of the end of the retort substantiallyas and for the purposes described.

GEO. M. HOLSTEIN.y JoI-IN D. JAMES. Vitnesses T. L. MAssIE, D. W.BARNARD.

